There are many different types of printing processes that are used to print ink-based images onto substrates, such as paper. Three types of presses that are well-known for large-volume printing include sheet-fed offset presses, heat-set offset presses, and cold-set web presses. Due to the vast differences among these presses, inks are specially developed for each type of press. Thus, cold-set web inks are used with cold-set web presses, sheet-fed offset inks are used with sheet-fed offset presses, and heat-set offset inks are used with heat-set offset presses.
Cold-set web inks have comparably high mineral oil content, low resin content, and low viscosity compared to sheet-fed offset and heat-set offset inks. Cold-set web inks are designed to dry by absorption onto paper and by air. On the contrary, the inks for sheet-fed offset presses and heat-set offset presses are petroleum oil-based or vegetable/soy oil-based and have resins and driers built in to ensure the inks cure to a hardened state. Sheet-fed presses typically have IR or UV driers, and heat-set presses typically have natural/propane gas drying units that help cure the ink. The inks for sheet-fed offset and heat-set web offset are designed to cure, preferably completely, either during the printing process or through oxidation and chemical reactions soon thereafter. Cold-set presses and inks are much different. Generally, cold-set printing does not require built-in driers for curing the ink, as cold-set inks are developed to dry by absorption onto paper and by air.
Cold-set web presses are generally considered to provide lower quality printing (e.g., lower resolution) in comparison to sheet-fed offset and heat-set offset presses. The viscosities of inks used with sheet-fed presses are typically much higher in comparison to cold-set web inks, and can therefore print with much higher resolution. Lower viscosity inks tend to expand too much on the substrate to provide the level of resolution provided by sheet-fed presses and inks. Heat-set web offset presses provide similar quality printing as sheet-fed offset presses, but are typically used for higher volume runs. Heat-set web inks often have silicone in them, and are developed specifically for the type of substrate that will be printed.
There remains a need for new printing systems that can provide novel consumer products with creative end uses.